Android 13 requires runtime POST_NOTIFICATIONS permission for DownloadService notifications

[yoobi]

Reading though Android 13 changes, I've noticed that we now need to add android.permission.POST_NOTIFICATIONS in the manifest.

As Exoplayer provides a DownloadService should the next versions of Exoplayer/Media3 add this permission and implements something about it ?

[marcbaechinger]

I'm not sure if it's the right thing to do to add this permission to a manifest of the library that then is automatically merged into an app manifest. Not every app may use the DownloadService.

I think an app that includes the DownloadService wants to add this permission, but I also think it should be left to the app to do that.

I agree though that we should add this permission to the AndroidManifest.xml of the main demo app as an example to do the right thing. Is this what you are asking for?

[yoobi]

It was an open question whether a comment should be added to the abstract class DownloadService in order to specify that if the permission is not asked for A13+ it won't prompt the notification.
I agree that handling the permission should fall upon the app using `DownloadService, also yes the demo might need an update regarding this permission.

[marcbaechinger]

Ok, makes sense. Currently the main demo app does never show a notification when downloading (when on targetSdkVersion 33). On API 33 it not only requires the permission to be added to the manifest, but instead the permission also needs to be requested at runtime. Aside: The session demo app is not affected by this change because its notification is exempted because it is attached to a media session.

I think we need to do the following things:

1. Document in DownloadService that an app with targetSdkVersion 33+ needs to add the android.permission.POST_NOTIFICATIONS to the manifest.
2. Document that such an app also needs to request Manifest.permission.POST_NOTIFICATIONS at runtime in order to notification to be shown. It's at the app's discretion when to do this, like when the app starts or when a download is triggered.
3. Do point 1) and 2) for the main demo app.

[marcbaechinger]

Marking this issue as a bug (in the main demo app) on API 33.